It is known that a 1-aminoalkylphosphonic acid or its peptide-related derivatives have an antibacterial action against gram-positive bacteria and gram-negative bacteria and also can enhance the activity of some antibiotics such as penicillin, cephalosporin and D-cycloserine, that alaphospharine, which is a dipeptide obtained from L-alanine and L-aminoethylphosphonic acid, is especially important, and that in general, an optically active 1-aminoalkylphosphonic acid derivative and particularly its derivatives in the L-form (R-form) thereof can exhibit broad biological activities (Japanese patent application first publication "Kokai" No. 61-88895).
Such a process for obtaining the optically active 1-amino-alkylphosphonic acid, which comprise effecting an asymmetric synthesis thereof with using an enzyme, include methods described in the "Tetrahedron Asymmetry" Vol.4, p.1965 (1993) and Japanese patent application first publication "Kokai" No. 61-88895 and others.
For example, Japanese patent application first publication "Kokai" No. 61-88895 describes such a process for the preparation of an optically active stereoisomer of 1-aminoalkylphosphonic acid of the formula: ##STR2## where R.sup.2 represents, for example, a branched or preferably straight alkyl group of 1 to 6 carbon atoms, particularly 1 to 4 carbon atoms and optionally substituted with a halogen, hydroxyl group, alkoxy group of 1 to 3 carbon atoms, phenyl group and/or phenoxy group, or alternatively R.sup.2 represents a phenyl group, which process comprises effecting the optical resolution of the N-acyl derivative of a 1-aminoalkylphosphonic acid or a racemic mixture of the 1-aminoalkyl phosphonic acid with use of an enzyme, and then deacylating the resulting optically active N-acyl derivative to prepare the stereo-isomer, characterized in that the enzymatic, optical resolution is effected with penicillin-G-amidase. However, this enzymatic and asymmetric synthetic process has a problem that a scope of the substrate which can be used as the starting material is limited.
Furthermore, as such a process for preparation of the optically active 1-aminoalkylphosphonic acid which comprises effecting the asymmetric synthesis thereof without using the enzyme, there are hitherto known several processes which are described in the following literatures (1) to (4). Thus;
(1) there is known a process for effecting the optical resolution of a racemic mixture of 1-aminoalkylphosphonic acid with using anhydrous dibenzoyl-L-tartaric acid, wherein the target optically active .alpha.-aminoalkylphosphonic acid is obtained in a yield of 70 to 87% (Canadian Journal of Chemical Engineering, Vol.61, p.2425, 1983);
(2) there is known a process for the preparation of optically active 1-aminoalkylphosphonic acid which comprises effecting asymmetric alkylation to give an optically active aminoalkylphosphonic acid ester, wherein the target substance is obtained in a yield of 50 to 86% and at an optical purity of 25 to 76% (Tetrahedron Letters, Vol.33, p.6127, 1992);
(3) there is known a process for the preparation of optically active 1-aminoalkylphosphonic acid which comprises effecting a diastereo-selective addition reaction of phosphonic acid ester to an optically active imine, wherein the target substance is obtained in a yield of 30 to 90% and at an optical purity of 71 to 99% (The Journal of American Chemical Society, Vol.116, p.9377, 1994); and
(4) there is known a process for the preparation of optically active .alpha.-aminoalkylphosphonic acid which comprises effecting an asymmetric hydrogenation reaction of an olefinic derivative of said compound with using an asymmetric catalyst, wherein the target substance is obtained in a yield of 92% and at an optical purity of 63 to 96% (Synthetic Communications, Vol.26, p.777, 1996).
However, the process described in the literature (1) has a problem that a number of the reaction steps are required and the operation of the process is complicated. The processes described in the literatures (2) and (3) have a problem that the optically active starting material is required to be used in a stoichiometric amount, and so on. Furthermore, the process described in the literature (4) has a problem that a number of the reaction steps are required in order to prepare the olefinic derivative which is a starting material and also that the nature of the starting material is limited. Hence, these above-mentioned prior art processes are not advantageous industrially.
For these reasons, there is an outstanding demand seeking for such a novel process for the preparation of the optically active 1-amino-phosphonic acid derivative, by which it is feasible to prepare a large amount of the optically active compound even with using a small amount of an asymmetric compound as the starting resource, and by which the optically active compound can be obtained by shorter steps of the reaction, as compared with the prior art processes. In addition, there is also a demand seeking for such a novel catalyst available for the asymmetric synthesis of said derivative, as well as a novel 1-aminophosphonate compound obtainable by said process.
Furthermore, the "Liebich Annalen der Chemie", pp.1153-1155 (1990) describes a non-asymmetric synthetic process for the preparation of a compound of the general formula: EQU R.sup.1 CHNH.sub.2 P(O)(OH).sub.2
where R.sup.1 stands for styryl group or the like, which comprises reacting N,N'-alkylidene bis-amide of the general formula: EQU R.sup.1 CH(NHCOR.sup.2).sub.2
where R.sup.1 stands for styryl group or the like and R.sup.2 stands for an alkylidene group, with PCl.sub.3 and acetic acid at 60 to 80.degree. C. for one hour and thereafter hydrolyzing the resulting reaction product to prepare the target compound in a yield of 39 to 99%.
Besides, Japanese patent application first publn. Kokai No. Hei-6-154618 describes, as a catalyst for use in an asymmetric nitroaldol reaction which comprises reacting an aldehyde compound with nitromethane, the following two catalysts:
(1) a catalyst for use in the asymmetric synthesis, which has been prepared from
a dialkali-metal salt of optically active 2,2'-dihydroxy-1,1'-binaphthyl, namely 1,1'-bi-2-naphthol of the formula (A.sub.R) or (A.sub.S): ##STR3## where M is Li, K or Na;
a lanthanum compound of the formula: LaX.sub.3 where X is F, Cl, Br, I, NO.sub.3 or CH.sub.3 CO.sub.2 ; and
an alkali metal alkoxide or alkali metal hydroxide of the formula: MOR or MOH where M is Li, K or Na and R is isopropyl or t-butyl group, in the presence of an aqueous solvent; and
(2) a catalyst for use in the asymmetric synthesis, which contains such active species as obtained by reacting optically active 2,2'-dihydroxy-1,1'-binaphthyl, namely 1,1'-bi-2-naphthol of the formula (B.sub.R) or (B.sub.S): ##STR4## with a lanthanum alkoxide of the formula: La(OR).sub.3 where R is an isopropyl or t-butyl group, in an ether-type organic solvent, and which catalyst is used characteristically in the presence of lithium chloride and an aqueous solvent.